Discovery TD5 Fuel Cooler Leak – Fix!

When recently fitting the TD5Alive Top Coolant Hose, along with a new Thermostat and Radiator we dislodged the end of the Fuel Cooler.

Obviously, I didn’t spot this till the next day when I spotted a puddle under the car, but couldn’t locate the leak! Eventually however when topped up and looking at the hoses it soon became apparent from the wet patch, along with dried OAT coolant, that the fuel cooler was leaking.

Leaky Fuel Cooler

Leaky Fuel Cooler

Now, how to fix it? Well, that’s easier said than done. You don’t need to remove the fuel line connections, but we undid the 4 bolts holding the fuel cooler to the engine, and then undid the clips holding the ends in place. Once undone, it takes just a few mins to remove the old O-Ring, and re-fit a pair of new O-Rings, as there’s space for two on the plug, though Land Rover in their infinite wisdom chose not to!

Here’s a shot of the Flat O-Ring in place on one of the ends and below a shot side by side with a new one.

Flat O-Ring

Flat O-Ring

Old vs New

Old vs New

As you can see, the O-Ring is fairly knackered, so replacing them is the best way forward.

New O-Rings

New O-Rings



Above you can see the pair of new O-Rings, and the Lube. Can never have enough lube.

Getting the clips back together is harder than it looks, and probably the most time consuming bit, but they will go back together eventually and then you simply bolt it back to the engine and re-connect and re-fill your coolant.

O-Ring Kit

O-Ring Kit

You can buy the o-rings and some lubricant from me on eBay

(10% of the Auction Price is being donated to Oldies Club, a Dog Rescue Charity)

Posted in Landie

32 Responses to “Discovery TD5 Fuel Cooler Leak – Fix!”

  • Tony lanceley says:

    Hi Alex,
    Just repaired the bottom steel radiator hose it was leaking from the brazing around drain plug, had it re-brazed, put back together with new oats coolant and guess what? another leak.
    This time its the fuel cooler as your blog.
    Can i ask where i can get these o-rings for the repair or maybe i could purchase some from you….thanks…tony Chester.

  • Hi Tony,
    Have dropped you an email, of course I have some spares, so not a problem to sort you a few for some beer tokens.

  • Darren says:

    Hi there, exactly same thing happened to me.
    Great to hear o-rings may be all we need, where can we get them?
    email me if you can help.
    l’r disco 2, td5

  • Hi Darren,
    Have dropped you an email 🙂

  • Simon says:

    I have the same problem like others.
    Could you help me out?

  • abbas says:

    Hi mate,are these fuel coolers also know to get blocked.the one i have is the cylinder type,but when passing water through it doesnt seem to rush out the other end,only trikle out,could this cause cold air hot and cold air inside and pressure build up?

  • Paul says:

    Hi all, i have come across this problem today , i wished i had looked on here before obtaining a second hand fuel cooler. I priced up the part with J L services who are landrover specialists. They told me they do not have to order this part very often and that it is a main dealer part , i was quoted over £600. Once i picked myself up of the floor i went to a landrover breakers and paid £50.00 for a used one. I did not realise this is such a common problem and one that is really easy to fix.

  • mick ramsey says:

    Hi alex , thanks for info on fuel cooler leak , i too now have it on my td5 , sometimes it can take a day to start leaking only does it when very cold , strange it does not leak when the engine has been running, would like to know where i can obtain o rings and lube many thank’s mick

  • pete says:

    my fuel cooler has started to leak so when we took it to bits one end has what looks to be a thermostat in it an the spring around the edge of it has broken, does anyone know where or wether you can just get parts as land rover deal only supplies the complete cooler at over £600. thanks pete

    • Hi Pete,

      IIRC the Fuel cooler doesn’t have a thermostat in it on the TD5, it’s just a in & through pair of plastic plugs, with the fuel being circulated inside the metal canister which acts as a heat exchanger.
      I’d suggest, if you’re totally stuffed, talking to Colin White Services in Glastonbury, they’re a massive breakers yard and deal almost exclusively in Landies, with lots of TD5’s down there.


  • Mark says:

    Fuel cooler leak on my way to Sheffield caused the motor to overheat coming off the motorway, wrecked the cylinder head gasket and causedme loads of grief!. such a difficult leak to find. Have been using my old trusty 200tdi while contemplating blowing up the TD5, however took heart on the TD5 and have just replaced the head gasket and bolts etc but having read your article will repair the cause properly, at the moment i’ve by-passed with tube. Many thanks for publishing this information, and will have a talk with JLservices, normally nice people, but like us, finding out the hard way the lack of testing that was done on the td5 prior to it’s launch.

    • Hi Mark,

      To be fair, the TD5 is now well over 10 years old – yes, maybe JLR skimped on the second set of o-rings, but most of the vehicles this is happening to are older vehicles, and the seal remains just fine until disturbed!
      The amount of testing done on the TD5 was substantial, it was after all based upon the K-Series petrol engines, and they had intended to produce a 4 and 6 cylinder version before BMW bought them.
      Sometimes with an engine, it’s hard to envisage what the engine will go through over a 10+ year service life, but I’ve seen engines with over 250,000 on the clock that are still going strong due to good maintenance.
      There’s a link to my eBay auction at the bottom of the blog post if you want a set of o-rings and lube to get your cooler back into shape. 10% of the proceeds are going to help support Oldies Club (a dog rescue charity) as well 🙂

  • pete says:

    in the end of the cooler that has the to pipes conected to it 90 degrees to each other, there is a dome shape item with a spring around what is this for as it looks like some kind of thermostat to me thanks pete

  • Hrm, it’s possible I guess, a Breakers yard would be your best bet for this part!

  • Stuart says:

    Require o rings for the feul cooler, can you help!

  • Dave says:

    Hi Alex
    I have the same problem with my fuel cooler on my defender 130 model 2003.
    This o rings are they the Vitol type ? would you sugest fitting 4?
    Do you still have stock


  • Kees says:

    I had the same problem this winter…(februari 2012)..defender 110 Td5….leaking fuel cooler on one side (front). Replaced the O ring and problem seems to be solved. Was an easy repair. There’s really nothing to it and the descriptions given on the net are very accurate. Most difficult thing was to get the clip back on which cost me some 10 minutes but eventually got it done. Before fixing I checked with the LR dealer…they would have charged me 500 euro’s for it and would have replaced the cooler. What a rip off that would have been. Now the total cost was less than one Euro for the viton O ring and one liter of cooling fluid !….Thanks for the internet !….

  • Kees says:

    Thanks for the reply, i replaced only on one side, I didn’t take the cooler of and it was only leaking on one side so I didn’t bother with the other side (yet :-)). I fit only one. Actually it was so easy that I thought if it doesn’t work I’ll add another. (off course I got spare o-rings now )

  • Paul Thompson says:

    Thanks for your helpful blog. Seems my fuel cooler on the 2001 TD5 has just sprung a leak. Two small pools of water under car, more than from the air conditioner in humid weather. I’m about to give it a good check out tonight. Coolant level is all ok.

    Can you let me know what cost and postage would be to send seals and lube to Perth Western Australia?

    Many thanks,


  • Dean Kenna says:

    Hi Alex, great write up, do you have any o-ring kits left, if so I’d really like to buy one. I look forward to hearing from you, best regards Dean

  • Dave says:

    Hi I have a 1999 S reg TD5 with a leaking cooler but it does not appear to have the clips at either end as per your photos. Do you know if the cooler has been superceeded please?

  • Victor says:

    Require those O rings for the fuel cooler. How can you help? Mine is a disco td5 year 2002

  • Ryan says:

    I have the fuel cooler leak issue and need to get the o-rings for my 2002 TD5 Defender 110. Can you assist? I was trouble shooting and had to change my water pump and water bottle cap. This is the last piece of the puzzle…

  • Steve baker says:

    Hi Alex
    Just came across this old thread, do you still have the. O rings and lube on your ebay shop please.

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